Marking-pen-type writing instrument

ABSTRACT

A writing and marking tip comprising a bundle of synthetic fibers disposed in generally longitudinally aligned relation, such fibers being bonded to each other at zones of contact by an adhesive, the tip being preformed to a predetermined cross section and being provided with longitudinally extending sidewalls and a planar end face lying in a plane inclined to the tip axis at an angle of from approximately 60* and comprising the marking face, such marking face having chamfered or beveled edge portions connecting the sidewalls and face for promoting the uniform ink laydown or trace during writing or marking.

United States Patent Davidson 1 Feb. 1., 1972 [54] MARKlNG-PEN-TYPEWRITING INSTRUMENT [72] lnventor:

[73] Assignee: The Gillette Company, Santa Monica,

Calif.

[22] Filed: Jan. 13, i971 [21] Appl.No.: 106,197

Henry Davidson, Huntington Beach, Calif.

Related US. Application Data [MI (,lontinuation-in-part of Ser. No.846,375, July 31,

I969, abandoned.

[52] US. Cl ..401/l99 [51 lnt. Cl ..B43k 8/00 [58] Field of Search..40l/l96207 [56] References Cited UNITED STATES PATENTS 2,025,28612/1935 Hutchinson ..40l/l98 2,453,201 11/1948 Cushman ..40l/2072,481,803 9/l949 Weaver ..40l/207 FORElGN PATENTS OR APPLlCATlONS1,027,095 2/ l 953 France ..40l/202 1,418,087 ll/l965 France ..40l/l99Primary ExaminerLawrence Charles Alr0meyl-lenry Davidson [57] ABSTRACT Awriting and marking tip comprising a bundle of s \nthetic fibersdisposed in generally longitudinally aligned relation. such fibers beingbonded to each other at zones of contact by an adhesive, the tip beingpreformed to a predetermined cross section and being provided withlongitudinally extending sidewalls and a planar end face lying in aplane inclined to the tip axis at an angle of from approximately 60 andcomprising the marking face, such marking face having chamfered orbeveled edge portions connecting the sidewalls and face for promotingthe uniform ink laydown or trace during writing or marking.

4 Claims, 4 Drawing Figures MARKING-PEN-TYPE WRITING INSTRUMENT RELATEDAPPLICATIONS This application is a continuation-in-part application ofapplication Ser. No, 846,375, now abandoned.

BACKGROUND OF THE INVENTION Writing instruments employing porous tips soas to produce wide, rather brushlike strokes or traces are well known inthe prior art. Generally, such prior art devices have employed rathersoft, easily deformable applicating ends or marking tips which exhibitpermanent deformation and loss of original tip .size prior to completeexhaustion of the marking fluid in the container in which the tip ispermanently mounted. Such prior art marking devices often employ felttips or nibs. It is also well known to use a marking tip or nib having arectangular cross section and a marking face disposed angularly withrespect to the axis of the nib; such prior art constructions being shownin U.S. Pat. Nos. 2,713,176, 3,003,181, 3,080,600, 3,089,182 and3,133,307.

The difficulties and disadvantages with the marking tips of prior artwriting instruments of the marking type is that the fiber bundlecomprising the tip or nib was of soft, easily deformable, fibers whichhad a short wear life and were adapted for use with a particular type ofink composition that was notentirely desirable. To overcome thesedifficulties, it was suggested that the fiber and binder of the tipsshould be stiffer, of high strength, and constructed of a less flexiblefiber. While this construction overcame the difficulties of prior artdevices, other problems arose such as the difficulty in providing a goodcontinuous trace left by contact of the marking tip with the paper. Suchtrace in the stiffer type of marking nib was discontinuous, varied inwidth and ink density, and still resulted in an excess amount of inkbeing left at the end of the race where the movement of the pen wasterminated. Moreover, the stiffer type of nib still gave rise to audibledissonances which were irritating since they produced noisy, scratchyand squeaky sounds when the nib was moved relative to the paper duringwriting. Another difficulty of the trace of such writing tips was thatthe edge of the trace was oftentimes irregular.

SUMMARY OF THE INVENTION Generally, the present invention provides awriting and marking tip comprising a bundle of synthetic fibers disposedin a generally longitudinally aligned relation, such fibers being bondedto each other at zones of contact by an epoxy resin which may be of athermoplastic or thermosetting type, the tip being preformed to apredetermined crosssection and being provided with longitudinallyextending sidewalls and a planar end face lying in a plane inclined tothe tip axis and comprising the marking face, and means for promotingthe uniform ink laydown or trace through the marking face comprising achamfered or beveled edge portion connecting the sidewalls and face,said chamfering resulting in the removal of a dense resin peripheralregion from the writing face, the width of the removed portion in theplane of the writing face being principally related to the dimensions ofthe writing face and the concentration of epoxy resin in the solutionused in forming the tip.

One object of the above generally described marking tip is g to providea tip which is relatively stiff, of high strength, and not easilydeformable for use in a marker-type pen.

Another object of the marking tip of the above-described invention is toeffect a continuous, regular, constant width, relatively constant inkdensity trace during marking.

Still another object of the above-described invention is to provide atip which substantially eliminates irritating audible, scratchy, andsqueaky noises during the useful writing life of the marker pen.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front elevation view,partly in section, of a writing instrument of the marking type employingan exemplary writing tip constructed in accordance with the presentinvention;

FIG. 2 is a side elevation view of an exemplary embodiment of a writingtip of the present invention;

FIG. 3 is an end view of the writing tip of FIG. 2; and

FIG. 4 is a partial view taken along the plane IV-IV of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to thedrawing, there is shown a writing instrument of the marking typecomprising a cylinder, indicated generally at 10; an absorbentink-carrying reservoir, indicated generally at 20; and a writing tip ornib, indicated generally at 30. The container 10 generally comprises acylinder 11 which may be of plastic material, as integral base 12 forsupporting the cylinder in the upright position, and a neck portion 13on which a cap (not shown) may be removably secured so as to prevent theinadvertent marking by the tip and to prevent evaporation of the ink inthe writing tip 30.

The reservoir 20 may be constructed of material and in a manner wellknown in the art, such as a plurality of polyester, polyamide,polyvinylacetate or polyethylene fibers which may be drawn into acylindrical shape, and inserted within the cylinder in a manner toprovide venting of the reservoir body.

The writing tip indicated generally at 30 and comprising the subjectmatter of the present invention may be fixedly mounted in the neckportion 13 of the container 10. The tip 30 has an inner end 31contacting the reservoir 20 so as to receive and supply ink by capillaryaction to the outer end of the writing tip. The outer end 32 of thewriting tip extends exteriorly of the neck portion 13 of the containerto provide a writing face, indicated generally at 33.

The writing tip is constructed from a rod which comprises a plurality ofsynthetic fibers, such as polyesters or polyamides, that are formed intothe rod through a process including heating, sintering, saturating,evaporating and curing. Of specific interest to the problems solved bythe present invention, the rod is saturated or impregnated afterpreheating and sintering in a saturation tank through which the rod ispulled. The tank contains an epoxy solution containing a cross-linkingagent which may comprise epoxy resin in a concentration in the range of6 percent (i /z percent) to 12 percent (:1 percent) in a solvent such asmethylethylketone, when the rod has dimensions as will be describedhereinafter. During the saturation process, the impregnating solutionfills approximately all of the voids between the synthetic fibers in thesintered rod.

Following saturation, the rod is then passed through an evaporator toremove the methylethylketone. The evaporation may be accomplished bypassing air at an elevated temperature in a countercurrent directionthrough a tube surrounding the rod which may accomplish the evaporationof approximately percent of the methylethylketone. It is during thisprocess of evaporation that the problem with respect to proper writingcharacteristics is believed to develop. During the evaporation, there isa densification of resin at the peripheral regions of the rod whichgives rise to excessive hardness of the peripheral region of the rod,prevents proper capillary ink flow in such peripheral region, andprevents contact of the fibers in the peripheral region with the surfacebeing marked so as to give rise to ink laydown irregularities. As thepercentage of resin in the impregnating solution is increased, thisdensification of resin in the peripheral regions of the rod increases soas to aggravate the above described problems. For example, with a 6percent resin concentration, the dense resin region or shell isapproximately 8 to 12 mils and with a 12 percent concentration isapproximately 10 to 15 mils for a rod having dimensions as hereinafterdescribed.

To overcome these problems, the writing tip 30 is provided with an outerend 32 which has beveled or chamfered edges so as to remove thehigh-resin peripheral region of the rod from the writing face 33. Thewriting face 33 comprises a central region 34 and a peripheral regionindicated generally at 35. The peripheral region 35 includes twolongitudinal side edge portions 36, 37 and a far end edge portion 38.

The writing face 33 is generally oblique to the longitudinal axis of thewriting tip 30 at an angle A, preferably of 60. This angular relation ofthe writing face to the horizontal when the writing tip 30 is verticallyoriented has been found to be an angle suitable for the general user. Ithas been experimentally found that the chamfered edge portions 36, 37should be disposed at an angle, indicated at B, in the range of 40 to 50and preferably 45. It also has been found that the dimension C of thelongitudinal chambered edge portions 36, 37, when a 6 percentconcentration of epoxy resin is used in making the rod, may be a minimumof 12 mils, but it is preferred that a larger dimension be used tocompensate for any variations in the process of forming the rod whichwould result in a thicker dense region, such as 35 mils, which has beenfound satisfactory in commercial production of tips. The dimension ofthe chamfer portions to obtain good writing characteristics depends onthe width or area of planar face 34, the size of the fibers used, theconcentration of epoxy resin used in impregnation, the evaporation rate,and other factors which affect the tip body peripheral region hardnessand thickness. The principal factor, however, is believed to be theepoxy resin concentration. When the concentration is increased from 6percent to 12 percent, for example, the minimum chamfer width (in theplane of the writing face) would be 15 mils.

The chamfered far end edge portion 38 is disposed at an an gle,indicated at D, relative to the plane of the marking face central region36, in the range of 92 to 98, preferably 95. The dimension E of thechamfered end edge portion 38 (in the plane of the face 34) must be atleast 12 mils with a 6 percent epoxy resin concentration and 15 milswith a 12 percent concentration but it has been found that a dimensionof approximately 44 mils is desirable in production.

The above exemplary dimensions, angles and chamfer limits for thewriting point 30 have been given for a writing point having a length ofapproximately 1.20 inches, a cross-sectional longitudinal dimension ofapproximately 220 mils and a lateral dimension of approximately 130mils. The face 34 has a longitudinal dimension of 254 mils beforechamfering and a lateral dimension of I30 mils. In chamfering thepreferred amounts, approximately 62 percent of the original writing faceis removed and face 34 is less than 50 percent of the original area. Asseen in the exemplary embodiment, both inner and outer ends 31 and 32are formed with identical marking faces so that during assembly of themarking pen, either end of the writing tip 30 may be inserted into theneck portion of the container. The ends of the writing tip 30 are formedby cutting the oblique writing face with a rotary saw operating atapproximately 1,500 to 5,000 rpm. or a guillotine-type chopper operatingat from to 100 strokes per minute. The writing tips are then chamferedusing a 40 to 60 grit silicon carbide grinding wheel operating in arange of 1,500 to ,000 rpm.

it will be apparent from the above detailed description of the writingface of the exemplary writing tip 30 that the near end edge portion 39,as viewed in FIG. 3, is not chamfered as are the other three edgeportions. The reason for this omission of the chamfering of this edgeportion will become apparent when it is considered that in use, themarking pen will be held such that a trace will normally not becommenced by contact of the near edge with the writing surface.Normally, the pen will be held such that the chamfered end edge portion38 is farthest away from the user. The pen will not be held such thatits longitudinal axis is less than the angle between the central region34 of the writing face 33 with the writing surface. Accordingly, thenear end edge portion 39 of the writing face will normally not contactthe writing surface and therefore there is no reason for chamfering ofsuch edge.

While a specific exemplary embodiment of a writing tip having a writingface has been shown and described above, it will be appreciated that theparticular dimensions, angles, and the like relating the chamfered edgeportions with the central region of the writing face will depend uponthe particular synthetic fibers chosen for the rod of the writing tipand the manufacturing process by which such rod is formed. This,modifications and variations of the present invention are possible inlight of the above teachings. lt is therefore to be understood thatwithin the scope of the appended claims, the invention may be practicedotherwise than as specifically described.

lclaim:

1, A writing and marking tip comprising an elongated bundle oflongitudinally extending synthetic fibers bonded with a resin so as tocomprise a rod having a peripheral region with a density and hardnessgreater than the density and hardness of the central region of the rodand through which ink flow is attenuated said rod being preformed to arectangular cross section and provided with a generally planar writingand marking face lying in a plane inclined to the longitudinal axis ofthe rod, and

means for facilitating a continuous, uniform and regular ink laydown bysaid writing and marking face comprising three chamfered edge portionsincluding longitudinal side edge portions and the far end edge portion,said chamfer removing, in the plane of the writing and marking face, atleas 12 mils from the longitudinal side edge portions and the far endedge portion, whereby during normal usage only the writing and markingface comprised of the softer central region of the rod will contact thewriting surface.

2. The writing and marking tip of claim I wherein the chamfer removes 35mils from the longitudinal side edge portions and 44 mils from the faredge portion.

3. The writing and marking tip of claim 1 wherein the writing andmarking face has an area of less than 50 percent of the original areaprior to chamfering the edge portions of said face.

4. The writing and marking tip of claim 2 wherein said rod isimpregnated with a solvent containing a 12 percent concentration ofepoxy resin prior to evaporation.

1. A writing and marking tip comprising an elongated bundle oflongitudinally extending synthetic fibers bonded with a resin so as tocomprise a rod having a peripheral region with a density and hardnessgreater than the density and hardness of the central region of the rodand through which ink flow is attenuated said rod being preformed to arectangular cross section and provided with a generally planar writingand marking face lying in a plane inclined to the longitudinal axis ofthe rod, and means for facilitating a continuous, uniform and regularink laydown by said writing and marking face comprising three chamferededge portions including longitudinal side edge portions and the far endedge portion, said chamfer removing, in the plane of the writing andmarking face, at leas 12 mils from the longitudinal side edge portionsand the far end edge portion, whereby during normal usage only thewriting and marking face comprised of the softer central region of therod will contact the writing surface.
 2. The writing and marking tip ofclaim 1 wherein the chamfer removes 35 mils from the longitudinal sideedge portions and 44 mils from the far edge portion.
 3. The writing andmarking tip of claim 1 wherein the writing and marking face has an areaof less than 50 percent of the original area prior to chamfering tHeedge portions of said face.
 4. The writing and marking tip of claim 2wherein said rod is impregnated with a solvent containing a 12 percentconcentration of epoxy resin prior to evaporation.